Research will continue on the mechanism of action of luteinizing hormone and human chorionic gonadotropin in the stimulation of RNA synthesis in isolated nuclei prepared from corpus luteum tissue. It has been shown that the hormones LH and hCG stimulate glucose 6-phosphate dehydrogenase in the isolated nuclei to provide the rate-limiting 5'-phosphoribosyl pyrophosphate required for de novo biosynthesis of purine and pyrimidine nucleotides. The substrates (2-14C)glycine, (6-14C)orotate and (U-14C)glucose 6-P were used to label the biosynthetic pathways for purine and pyrimidine synthesis. The research will be extended to examine the possible effects of LH or hCG on the template capacity of purified chromatin prepared from nuclei of corpus luteum tissue. These hormones may also have a stimulatory effect on RNA polymerases, and this will be examined.